Calcite vs Dolomite
| Property | Calcite | Dolomite |
|---|---|---|
| Formula | CaCO3 | CaMg(CO3)2 |
| Crystal System | Trigonal | Trigonal |
| Mineral Class | 05 Carbonates and Nitrates | 05 Carbonates and Nitrates |
| Mohs Hardness | 3.0 | 3.5-4.0 |
| Color | Colorless, white, yellow, orange, blue, green | Colorless, white, pink, gray, brown |
| Luster | Vitreous | Vitreous |
| Streak | White | White |
| Transparency | Transparent | Transparent |
| Cleavage | Perfect rhombohedral {1011} | Perfect rhombohedral {1011} |
| Fracture | Conchoidal | Subconchoidal |
Key Differences
- ◆ Calcite reacts strongly with cold dilute HCl; dolomite only reacts when powdered.
- ◆ Dolomite contains both calcium and magnesium (CaMg(CO3)2); calcite is pure CaCO3.
- ◆ Dolomite crystals often show distinctive curved saddle-shaped (baroque) faces; calcite does not.
- ◆ Calcite has a slightly lower specific gravity (2.71) than dolomite (2.84–2.86).
- ◆ Calcite is trigonal with scalenohedral and rhombohedral habits; dolomite is also trigonal but rarely forms good scalenohedral crystals.